gd_tell64 man page

This version of gd_tell(3) uses a 64-bit offset type (gd_off64_t), where one is available, regardless of the size of off_t. It is only available if one defines GD_64BIT_API or _LARGEFILE64_SOURCE before including getdata.h.

If off_t is a 64-bit type (possibly because _FILE_OFFSET_BITS has been defined to 64), this function will the same as gd_tell(3). Otherwise, gd_tell(3) will be a version of this function which uses a 32-bit off_t.